Career Development: The applicant's primary interest is in designing perioperative anesthetic techniques to improve postoperative surgical outcomes, thereby making unique contributions to the dynamic study of anesthesia, pain management, and rehabilitation outcomes research. The ultimate objective of this K-23 Career Development Award is to prepare the applicant for a career as an independent investigator, designing and implementing hypothesis driven clinical investigations to evaluate the clinical, functional, and cost benefits of these anesthetic interventions. This will be accomplished with didactic coursework, participation in seminars, research focus groups, scientific conferences, and focused tutorials by experienced practitioners in multiple relevant, diverse fields of study. Because interdisciplinary collaboration is required to advance the field of postoperative outcomes research, the applicant will assemble an integrated, multidisciplinary team of highly-trained researchers and clinicians dedicated to this goal. Finally, implementing a clinical investigation using acquired didactic knowledge and close mentor supervision will allow integration and application of these educational components. Clinical Investigation: Following knee and hip replacement, ambulation is often limited by joint pain, greatly decreasing functional mobility, rehabilitation quality, and possibly the ultimate functional outcome. "Perineural infusion" is a relatively new analgesic technique that involves the percutaneous insertion of a catheter directly adjacent to the peripheral nerves that supply the affected joint. Local anesthetic is then infused via the catheter to provide potent, site-specific analgesia free of significant side effects. The ultimate objective of the proposed research is to determine if perineural local anesthetic infusion in the immediate postoperative period has both short- and long-term benefits following knee and hip replacement surgery for osteoarthritis. The research plan consists of two (knee or hip replacement) randomized, double-blind, placebo-controlled, parallel-arm clinical investigations. Patients will randomly receive either perineural local anesthetic or normal saline for 4 days following surgery. Primary outcomes include functional mobility (ambulatory distance) and the time until specific, predefined readiness-fordischarge criteria are met following surgery. Secondary outcomes include the relationship between analgesic technique administered in the immediate postoperative period and subsequent pain, stiffness and functional disability.